Unidentified Arabic (Probably Silver) Coin (Id: Islamic Temple Token)

It isn't a "coin". It is a class of object known in the West as an "Indian temple token", though most of us know by now that Muslims don't have "temples" and this one is clearly Islamic.

They are part of a long tradition in South Asia of making religious amulets. In the Islamic tradition, they are apparently given as gifts to those going on the Hajj to Mecca, as a reminder of the reasons for and destination of their journey. The obverse, based loosely on Indian silver coinage of the Mughal period, names Mohammed in the centre and the Four Caliphs around. The reverse depicts a stylized mosque, presumably a representation of the Grand Mosque in Mecca. Do a forum search for "Islamic temple token" and you'll find quite a few old threads with items very similar to yours, such as this one.

Early Hajj Pilgrim tokens (from the pre-WWII period) are made of silver; the mass-produced modern ones are made of cupronickel or silver-washed brass. Unless you've got a provenance for it going back many decades, I would assume it was a base-metal version until and unless it were proved otherwise.

Apart from taking it to a jeweller, coin dealer or scrap metal merchant to test, I don't know. You can't really judge by weight or density, since copper and silver are too close in density for anything to really count. The jeweller might have to do a chemical/touchstone test, or they might have one of those nifty portable XRF machines (just like a Star Trek tricorder, only real!). Either way should tell you whether there's silver in the surface or not, but might still give a false positive if it's silver-plated with a copper core.